Filters for tobacco smoke



- Feb. 27, 1968 F. HASLAM 3,370,594

FILTERS FOR TOBACCO SMOKE Filed Feb. 16, 1965 FIGJ Y INVENTOIE FREDHASLAM ATTORNEYS United States Patent 3,370,594 FILTERS FOR TOBACCOSMOKE Fred Haslam, Bassett, Southampton, England, assignor to Brown andWilliamson Tobacco Corporation, Louisville, Ky., a corporation ofDelaware Filed Feb. 16, 1965, Ser. No. 433,109 4 Claims. (Cl. 131-261)ABSTRACT OF THE DISCLOSURE A filter mouthpiece for cigarettes havingmeans by which smoke entering the mouthpiece will pass only once throughthe filtering material before emerging from the filter element, themouthpiece having means for directing the smoke through an inlet openingat one end thereof and means for directing the smoke through an outletopening at the other end thereof.

This invention concerns improvements relating to filters for tobaccosmoke and to mouthpieces for cigarettes or the like incorporating suchfilters.

It is well known to provide filters for tobacco smoke which are madefrom fibrous or sheet material so packed in a mouthpiece that the fibresor sheets lie longitudinally along the path of the smoke flow. Suchmaterials are frequently crimped or crumpled so as to form a series ofobstructions, perpendicular to the smoke flow, which impede the smokeparticles and thus improve the filtration. However, such obstructionsaffect the filtration to a small extent only and major variations infiltration effect can only be achieved by alteration of the surface areaavai able for impingement by the smoke, i.e. by the incorporation ofmore or less filter material. Such changes in the amount of filtermaterial can have disadvantageous effects, such as an undesirable risein the draw resistance if the amount of material is increased, orundesirable softness of the completed filter if the amount is reduced.

An object of the invention is to provide a kind of filter in which thesurface area of the filtering material can be readily varied to givegreater or less filtration of the smoke without affecting the firmnessof the filter, and which allows of a reduction in draw resistance withincreasing area available for filtration.

According to the invention, in a filter mouthpiece for a cigarette orthe like, at least one sheet of smoke-filtering material is arranged inand substantially longitudinally of a hollow mouthpiece, by the wall ofwhich it is supported, in such a manner that smoke flowing through themouthpiece will be constrained to pass through the said sheet. For thispurpose, sections of the interior of the mouthpiece separated from eachother by the filtering material may be closed at opposite ends to eachother of the said mouthpiece by transversely disposed smoke-imperviousmaterial. The filter material, preferably paper, may be of anyappropriate thickness and porosity and may be pleated or folded to givea required area of material available for filtering the smoke particlesand, if desired, to provide a pleasing symmetrical appearance at the endof the cigarette to which it is to be attached. If a plurality ofseparated sections or space is thus formed by pleating or folding,alternate sections or spaces are closed by smoke-impervious material atopposite ends of the mouthpiece so that air or smoke entering themouthpiece will pass once only through the filtering material beforeemerging.

Several examples of ways of carrying the invention into effect will nowbe more fully described with reference to the accompanying drawing, inwhich each of FIGURES 1 and 3 to 7 is a diagrammatic cross sectionthrough a cigarette mouthpiece and FIGURE 2 is a longitudinal sectioncorresponding to FIGURE 1.

In the simple form shown in FlGURE l, the mouthpiece consists of acylindrical outer support 1 with a single sheet 2 of smoke-filteringpaper material arranged diametrically along the longitudinal axis of thesupport and secured thereto at its longitudinal edges 3 by adhesive, forexample a lacquer with a cellulose acetate base. One semicircularsection at each end of the mouthpiece is closed by half discs, 4 and 5respectively, of a smoke-impervious material in such a manner that smokeentering the mouthpiece 1 from the cigarette 6 by the semicircularopening 7 left at that end must pass through the sheet 2 of filteringmaterial during its flow through the mouthpiece before leaving thelatter by the semicircular opening 8 left at the other end. The halfdiscs 4, 5 may be made of paper coated or impregnated with the saidlacquer and may be secured to the support 1 by the same lacquer.

In each of FIGURES 1 and 3 to 7, the area closed at one end of themouthpiece has been indicated conventionally by diagonal hatching, whilethe area closed at the other end is unhatched.

If a larger filtering area is required, a sheet 2 of the filteringmaterial may be folded along its length to a V shape (FIGURE 3), a Wshape (FIGURE 4) or an N shape (FIGURE 5), in which case thelongitudinal crest or crests 9 are secured to the support 1 as well asthe edges 3.

Alternatively, as illustrated in FIGURE 6, two sheets 2a, 2b offiltering material may be folded to a V shape along their length andconnected together by adhesive at the crests 10 to form an X shape.

In practice, it may be desirable that the filtering material should havean area even greater than that available with the forms illustrated inFIGURES 1 to 6. This may be achieved by pleating or crimping a largerarea of material into the mouthpiece in a symmetrical formation. Onesuitable such formation is illustrated in FIGURE 7, in which a sheet ofpaper filtering material 2c is folded to a petal like formation whoseouter crests 11 are secured to the support 1, while the inner crests 12come to gether near the axis of the mouthpiece. Alternate sections ofthe interior of the mouthpiece are closed at opposite ends thereof, ashas again been conventionally indicated in FIGURE 7.

For any given form of the filtering material, the filtration eifect canalso be increased or decreased by increasing or decreasing the length ofthe mouthpiece or filter. With increased area, an increased filtrationeffect can be obtained together with decreased draw resistance. Suchvariation in filtration effect can be obtained, moveover, withoutaffecting the firmness of the mouthpiece.

The filtration effect can also be influenced by selecting filteringmaterial with properties to suit the particular requirements. Thematerial should be fairly stiff and of a porosity not less than a Pottsvalue of 2,000.

Except for reasons of convenience of production, it is not necessary forthe filtering material to extend strictly longitudinally of themouthpiece. It may be disposed somewhat obliquely or in a conical orfrusto-conical form.

The filtering material may be treated with one or more substancescapable of altering the composition of the smoke and/or improving itsflavour. Examples of such substances are alkaline or acid materials suchas calcium carbonate or citric acid, flavour substances such as mentholor its compounds, chemical reagents for the absorption of specific smokecomponents or absorbent materials such as charcoalasilica gel orzeolites, which may themselves be treated with chemical smoke-modifyingsubstances.

7 Examples of results obtainable with such filters will now be given:EXAMPLE I Filters were made by pleating sheets of paper, of 16 sq. cm.area, of a general utility filter grade such as Whatmans No. 1 paperwith a Potts porosity value of 3,000 to form shown in FIGURE .7 andfitting them into cylindrical hollow mouthpieces of 8 mm. diameter and25 mm. length opposite ends of alternate sections of the interior of themouthpiece being closed as described above. The average pressure drop ofthe final filters was 6 cm. water gauge.

On smoking cigarettes through these filters, with a pufi? of 35 cc.volume and 2 seconds duration taken twice per minute and using anabsolute filter to trap the smoke passing through the cigarette filters,an average of 53% of the total tar in the smoke was found to be retainedby the cigarette filters.

EXAMPLE II Filters were prepared as in Example I, but using a strong,rough surfaced, paper with a Potts porosity value of 2,500. The averagepressure drop of the final filters was 9.0 cm. water gauge. I

On smoking cigarettes through these filters as described in Example I,an average of 82% of the total tar produced was retained by thecigarette filters.

EXAMPLE III Filters were prepared as in Example I, using singlyacidwashed paper with a Potts porosity value of 2,500, and furtherfilters were prepared from similar, but doubly acid-washed paper with aPotts porosity value of 3,200. The average pressure drops for thefilters were; respectively, 8.0 cm. and 8.2 cm. water gauge. a

On smoking cigarettes through these filters as described in Example I,the average proportion of the total tars in the smoke retained by thefilters was 63% in each case.

EXAMPLE IV Filters were prepared by the method of Example I, using ahigh wet-strength paper with a Potts porosity value of 2,000. Theaverage pressure drop of the completed filters was 8.0 cm. water gauge.

On smoking cigarettes through these filters as described in Example I,the average proportion of the total tar in the smoke retained by thefilters was 51%.

EXAMPLE V Flters were prepared from two sheets of paper of achromatographic grade and of 8 mm. width and 15 mm.

length inserted in the form shown in FIGURE 6 into a mouthpiece of 8 mm.diameter and 15 mm. length. The filters had an average pressure drop of11 cm. water gauge.

On smoking cigarettes provided with these filters as described inExample I, the average retention of the total tars produced in the smokewas I claim:

1. A filter mouthpiece for a cigarette comprising: a hollow, cylindricalsupporting member and at least one sheet of tobacco smoke filter paperhaving a Potts porosity value of at least 2,000, the filter paper beingarranged in and substantially longitudinally of the member and extendingtransversely of the interior thereof so as to divide the interior intoat least two longitudinally extending passages, closure means mounted insealing relationship between said filter paper and the inner surface ofsaid hollow member and disposed at opposite ends of said hollow memberand at opposite sides of said filter paper to present smoke inlet andsmoke outlet openings respectively at opposite ends of said hollowmember and on opposite sides of said filter paper so that tobacco smokeentering the inlet opening is constrained to pass through the filterpaper and through the outlet opening, the filter paper mounted insealing engagement throughout its length to the inner surface of thehollow member whereby the filter material is supported longitudinally ofthe mouthpiece and itsopposite ends are supported by the closure means.

2. A filter mouthpiece according to claim 1, wherein the filteringmaterial is folded to produce an angular form as seen longitudinally ofthe mouthpiece.

3. A filter mouthpiece according to claim 1, wherein the filteringmaterial is pleated to a symmetrical formation as seen longitudinally ofthe mouthpiece.

4. A filter mouthpiece according to claim 1, wherein the filteringmaterial is pleated to a symmetrical petal like formation as seenlongitudinally of the mouthpiece.

References Cited UNITED STATES PATENTS 1,605,059 11/1926 Oakes et al.l31-10.5 1,657,290 1/1928 Waugh 13l207 X 2,181,614 11/1939 Streifiing c131-10 FOREIGN PATENTS 1,118,860 3/1956 France. 643,203 7/1962 Italy.

SAMUEL KOREN, Primary Examiner.

MELVIN D. REIN, Examiner.

